Dental materials comprising resin and, in certain circumstances, filler, are used as restorative materials to repair tooth structure, or as sealants or adhesives. These materials are applied in an uncured state, and then cured in the mouth, often by exposure to a curing light that initiates a polymerization reaction. The consistency of the materials when first applied in an uncured state may be problematic in that they may flow more than desired. This is particularly the case for adhesives or sealants, which may tend to flow in an uncontrolled manner. More highly filled materials, in the category of dental restoratives, tend to exhibit a slower flow characteristic called "slump." Slump may be a problem because the shape imparted to the dental material may change in the time between shaping by the practitioner and polymerization of the material by exposure to light.
Certain restoratives, particularly those for materials that are to be used as posterior composites, are designed to be of particularly high viscosity. Ideally, a resin based material would be formulated such that it mimics the placement characteristics of amalgam filling materials, which are condensed in the mouth by packing. During this packing process, the amalgam condenses such that it will displace a matrix band, a thin metal strip that acts as a form for the restoration and assures appropriate contact of the restoration with adjacent dentition. The current art in achieving the desired packable viscosity of resin based products uses higher filler loading and/or fillers with beneficial sizes and shapes. The problem associated with this approach is that those materials often appear dry and tend to be crumbly when handled. Another approach is to increase resin viscosity to create heavy body material. The material from this approach may be too sticky for optimal use, and also may be dry and crumbly.